<h2>上传封面</h2>
<form method="post" enctype="multipart/form-data" action="do_cover" target="_self">
    <p>
        <input type="file" name="cover" id="cover" accept="image/jpeg,image/jpg,image/png"/>
        <input type="submit" value="上传" />
        <br/><span style="color:#777;font-size:.8em;">图片格式限为PNG、JPEG，2M以下</span>
    </p>
</form>